title: A new technique for the assessment of the 3D spatial distribution of the calcium/phosphorus ratio in bone apatite.
abstract: The value and distribution of calcium/phosphorus (Ca/P) ratio in bone vary between healthy and osteoporotic bone. The purpose of this study was the development of a technique for the assessment of the 3D spatial distribution of Ca/P ratio in bone apatite, which could eventually be implemented through a conventional computed tomography (CT) system. A three-material mass-fraction decomposition CT dual energy analysis was optimized. The technique was validated using ten bone phantoms of different, known Ca/P ratio. Their measured average Ca/P ratio showed a mean/maximum deviation from the expected Ca/P ratio of 0.24/0.35. Additionally, three healthy and three inflammation-mediated osteoporotic (IMO) collagen-free rabbit tibia bone samples were assessed, providing promising preliminary results on real bone tissue. The average Ca/P ratios in all IMO samples (1.64-1.65) were found to be lower than in healthy samples (1.67-1.68). Osteoporotic regions in IMO samples were located using Ca/P ratio colour maps and Ca/P ratio values as low as 1.40 ± 0.26 were found. The low Ca/P ratio volume proportion in IMO samples (12.8%-13.9%) was found to be higher than in healthy (5.8%-8.3%) samples. A region growing technique showed a higher homogeneity of Ca/P ratio in healthy than in IMO bone samples.
authors.affiliation: Department of Medical Physics and Bioengineering, University College London, Gower Street, London, WC1E 6BT, UK.
authors.forename: A
authors.initials: A
authors.lastname: Hadjipanteli
authors.forename: N
authors.initials: N
authors.lastname: Kourkoumelis
authors.forename: P
authors.initials: P
authors.lastname: Fromme
authors.forename: A
authors.initials: A
authors.lastname: Olivo
authors.forename: J
authors.initials: J
authors.lastname: Huang
authors.forename: R
authors.initials: R
authors.lastname: Speller
mesh_terms: D000818:Animals; D001031:Apatites / Q000378:metabolism*; D001842:Bone and Bones / Q000000981:diagnostic imaging / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism*; D005260:Female; D021621:Imaging, Three-Dimensional / Q000379:methods*; D010024:Osteoporosis / Q000000981:diagnostic imaging; D019047:Phantoms, Imaging; D010758:Phosphorus / Q000378:metabolism*; D011817:Rabbits; D014057:Tomography, X-Ray Computed
chemical_list: D001031:Apatites; D010758:Phosphorus; D002118:Calcium